//------------------------------------------------------------------------------
//  <copyright file="CollisionCheckingBruteForce.cs" company="Microsoft Corporation">
// The MIT License (MIT)
// 
// Copyright (c) 2014, Microsoft Corporation
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
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//  copies of the Software, and to permit persons to whom the Software is
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// The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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//------------------------------------------------------------------------------

namespace Microsoft.Robotics.Collision
{
    using System;
    using System.Collections.Generic;

    using Microsoft.Robotics.Geometry;
    using Microsoft.Robotics.Numerics;

    /// <summary>
    /// A simple collision checker using brute force approach
    /// </summary>
    public class CollisionCheckingBruteForce : CollisionChecking
    {
        /// <summary>
        /// Check collision in a brute force style, that is, checking all the pairs from groups1 and groups2
        /// </summary>
        /// <param name="groups1">First element group list</param>
        /// <param name="groups2">Second element group list</param>
        /// <param name="distances">Distances between individual element group pairs</param>
        /// <returns>A number that indicates how much collision there is</returns>
        public override double CheckCollision(List<GeometryElementGroup3D> groups1, List<GeometryElementGroup3D> groups2, out double[][] distances)
        {
            // scores to calculate
            double collisionDistance = double.MaxValue;

            // initialize report
            distances = new double[groups1.Count][];
            for (int i = 0; i < groups1.Count; ++i)
            {
                distances[i] = new double[groups2.Count];
            }

            // iterate through all the object pairs
            for (int i = 0; i < groups1.Count; ++i)
            {
                for (int j = 0; j < groups2.Count; ++j)
                {
                    double value = groups1[i].DistanceFrom(groups2[j]);
                    distances[i][j] = value;
                    collisionDistance = Math.Min(collisionDistance, value);
                }
            }

            // return the collision distance
            return collisionDistance;
        }
    }
}
